<?php
$db=new PDO('mysql:host=localhost;dbname=db', 'root',  '12qwas');
$result=$db->query("select cy as 成语, first 首字 from chengyu limit 2");
foreach ($result as $row) {
    //print_r($row);
    echo "{$row[0]}--------{$row['首字']}\n";
}